This invention relates to the smoke blocking device and more particularly, but not by way of limitation, to a smoke blocking device used in sewer pipe when checking for leaks by introducing smoke in the pipe.
Heretofore, it has been a common practice when introducing smoke in a sewer pipe to use sandbags to block the pipe both upstream and downstream and to introduce smoke in the pipe to see if there are any leaks in the pipe by following the escape of the smoke from the pipe. This method of checking for pipe leaks subjects a worker to being lowered into a manhole and the possibilities of being exposed to deadly sewer pipe gas.
In U.S. Pat. No. 3,451,259 to McNulty, U.S. Pat. No. 3,453,869 to Cherne, U.S. Pat. No. 3,862,607 to Watts and U.S. Pat. No. 3,958,607 to Gray, different types of telephone cable assemblies, apparatus for sealing pipe leaks, apparatus for testing conduit and plugs for pipe lines are disclosed. None of the prior art patents addresses the problem of blocking smoke in a sewer pipe and eliminating the need of workers being subjected to deadly sewer gas.